Thetford Forest is a great place to take the kids, dog and yourself for a walk.
They also have concerts in the park in the summer. Also nearby is Go Ape where you can act like monkeys and climb the trees!
They also have provisions for riding bikes, bbqing, camping, picnicking, horse riding, and a play area for children.
You can also go to Brandon Country Park and walk around, run or cycle. They have a nice place to eat some lunch and a park for the kids. I have been told you must be careful with your dogs in the woods because of the muntjacs (chinese deer) can be startled and defend themselves.
Make use of the lovely summer days and the fresh air!